Merge pull request #488 from lenguyenthanh/improve-replay-game-move-w…

…hile-valid

Traverse sans only once in gameMoveWhileValid

src/main/scala/Replay.scala

@@ -46,24 +46,34 @@ object Replay:
         )
       )
 
-  def gameMoveWhileValid(
+  def gameMoveWhileValidReverse(
       sans: Seq[SanStr],
       initialFen: Fen.Epd,
       variant: Variant
   ): (Game, List[(Game, Uci.WithSan)], Option[ErrorStr]) =
     val init       = makeGame(variant, initialFen.some)
     val emptyGames = List.empty[(Game, Uci.WithSan)]
-    (for
-      moves <- Parser.moves(sans).leftMap(err => (init, emptyGames, err.some))
-      games <- moves.value
-        .zip(sans)
-        .foldM(emptyGames):
-          case (games, (san, sanStr)) =>
-            val game = games.headOption.fold(init)(_._1)
-            san(game.situation)
-              .leftMap(err => (init, games, err.some))
-              .map(m => (m.applyGame(game), Uci.WithSan(m.toUci, sanStr)) :: games)
-    yield (init, games.reverse, none)).merge
+    sans
+      .foldM((init, emptyGames)):
+        case ((head, games), str) =>
+          Parser
+            .sanOnly(str)
+            .flatMap: san =>
+              san(head.situation)
+                .map: move =>
+                  val newGame = move.applyGame(head)
+                  (newGame, (newGame, Uci.WithSan(move.toUci, str)) :: games)
+            .leftMap(err => (init, games, err.some))
+      .map(gs => (init, gs._2, none))
+      .merge
+
+  def gameMoveWhileValid(
+      sans: Seq[SanStr],
+      initialFen: Fen.Epd,
+      variant: Variant
+  ): (Game, List[(Game, Uci.WithSan)], Option[ErrorStr]) =
+    gameMoveWhileValidReverse(sans, initialFen, variant) match
+      case (game, gs, err) => (game, gs.reverse, err)
 
   private def computeSituations[M](
       sit: Situation,